Calorimeter



April 7, 1953 N. e. LINDSTRCSM 2,633,748

CALORIMETER Filed Feb. 5, 1948 2 SHEETS-SHEET 1 HEAT EXCHANGER 0 D v A, b

Izzy 61272301 N. G ,Lb' LcZW'm April 1953 N. e. LINDSTROM 2,633,748

CALORIMETER Filed Feb. 5, 1948 2 SI-lEETS-SHEET 2 .73! GL L'na laizo m Patented Apr. 7, 1953 CALORIMETER Nils Gottfrid Lindstriim, Stockholm, Sweden, as-

sig'nor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a company of Sweden Application May 5, 1948, Serial No. 25,111

In Sweden May 27, 1947 Claims. (01. 73-493) The present .invention relates to a device for measuring velocities of flow or heat quantities transported by a running medium. The invention is based on the physical law that the heat transition constant between a running medium and-a heat conducting body varies with the velocity of the medium, if the heat received by the body from the medium is conducted away to a heat distributor. The difference of temperature between the body and the medium is greatest when the velocity of the medium is zero and approaches zero when the'velocity is increasing to infinite. 'e

The medium is supposed to pass through a pipe and the invention consists partly in at least one heat conducting body being brought through a wall delimiting the medium and heat insulated from the wall and being in heat conducting con nection with a heat distributor at another temperature than the medium, and partly in thermoelements, of which one is arranged to give an electro-motive force proportional to the diiierence of temperature between a point insaid heat conducting connection and said heat distributor, and a second thermoelement is arranged to give an electro-motive force proportional to the difference of temperature between the medium and a point in the heat conducting-connection anda further thermocouple gives a third electromotive force, which is proportional to the dinerence of temperature between the medium and said heat distributor, which three'electro-motive forces through subtraction of the last mentioned from the sum of the two first-mentioned ones give an electrical current'proportional to the velocity of the medium or the heatquantity passing through the pipe.

The invention will be described more closely by the aid of the annexed drawings. Fig. 1 shows an embodiment of the invention intended for calorimetry, whereby the outlet pipe from a heat exchanger constitutes the above-mentioned heat distributor. Fig. 2 showsa number of diagrams over the relations between thed fference of temperature and the velocity of water within the calorimeter according toFig. 1. Figs. 3-4 show two different embodiments of the invention, whereby the medium in'theouflet pipe from a heat exchanger constitutesth'e heat distributor.

. In Fig. l, R is a heat exchanger with the feed pipe I and the outlet pipeZ, Between the pipes I and 2 there are. two heat conducting contacts? and II), which are heat insulatedfrom theieed pipe I through the packings land 9; but heat conducting connected, for instance welded to the outlet pipe 2. The contacts I and II) may be metaltubes. At each of the metal tubes 1 and III a plate 3 or 8 respectively is fastened. These plates are parallel to the axis of the tube I and are suitably made of smooth glass. The pipe I has a constriction at the plate 8, so that the velocity of the medium here is about four times greater'than at the plate 3. In the metal tubes I and I0 there are soldered junctions 6, 5 and I I to thermocouples. Within each of the tubes I and 2 there are two other soldered junctions for thermoelements, I2 and I5 in the feed pipe I, and I 9 and 20 in the outlet pipe 2. The soldered junctions I2, I5, I9 and 20 are well insulated from the tubes I and 2 through packings Id and I8, they are carried by Bakelite? tubes I3 and I1 and embraced by copper cylinders I6 and 24, whereby they accurately will assume the same temperature as the medium in the tubes I or 2. The soldered junctionsi and 6 form a thermocouple, which gives an eldt'ro-motive force vary-. ing between the water velocity h in the tube I according to the curve A in Fig. 2, if the differ ence of temperature li -ti between the temperature of the medium in thetube I and its temperature in the tube 2 is constant. If the temperature til-tic is varying the ordinate for every point on the curve A varies in direct proportion to tv-tk. 7'

The soldered junctions II and I2 form another thermoel'ement, which-gives an electro-motive force varying with the water velocity h in the tube I according to the curve B in Fig. 2, if the difference of temperature tvtk between the temperature of the medium in the tube I and its l temperature in the tube 2 is constant. A part of this electro-motiveiorce is tapped by means of an adjustable rheostat 2| and is so adjusted that the sum of thecurves A and B will be a practi-' cally straight line. 4 That .this is possible has been proved experimentally. The curve B has an asymptote: S=K2. If A+B-K2 isformed, the dotted line which partly coincides-with the curve A, is obtained through the point K1.

The soldered junctions I tend 20 form a third thermocouple, which gives an electro-motive force proportional to the difference of temperature tvtk between th -temperature of the medium in the tube I and its temperature in the tube 2. A part of this voltage, which'is constant if t0-tk is constant, is selected by means of an adjustable rheostat 22 and isadjusted so, that it has the value: v I r r s=K1+K2 If the three above mentioned electro-motive forces are connected so that the last mentioned electro-motive force counteracts the sum of the two first-mentioned ones, the straight line X is obtained through the origin 0. Experiments have shown that the curve X is regarded as a straight line until a certain limit, for example hm, which will correspond to the upper limit for the measuring range of the calorimeter.

If the difference of temperature tvtk between the temperature of the medium in the tube I and its temperature in tube 2 varies, all the abovementioned three thermocouples will be exposed to variations in the temperature, whereby a full proportionality between the differences of temperature acting on the thermocouples will exist at each value of the water velocity It, and thus the line X will change its angle coefficient linearly, when the difierence of temperature tvtlc is changed. It is here supposed that the tube 2 assumes the temperature tic, which is the temperature of the medium in the tube 2, independent of the temperature of the neighborhood and the heat coming from the tube I through the metal tubes i and Ill.

The electro-motive force from the thermocouples is conducted to the terminals A and B, to which an electrical indicating meter E is connected. The heat quantity Q, consumed in the device R or transmitted to the medium, can, if the medium is supposed to be water, he expressed by the formula:

According to the description above the angle coefiicient for the line X varies linearly with the difference of temperature (tvtk) due to:

kl=k3(to-tk) where ks.=-a constant From this is obtained:

k2 q k;; i

and

Q=k-a:

where k: a'constant An electrolytic meter E connected to the terminals AB can thus be so graduated that the heat quantity which is consumedor absorbed in R, can be read directly.

In the description above has been supposed that the tube 2 assumes the temperature of the medium independent of the temperature of the neighborhood and the heat transmitted from the tube i. This supposition cannot be made always. It is however possible to compensate this with an accuracy sufficient for practical use by introducing thesoldered junctions l9 and 25 into Fig. 1 and connecting these to a thermocouple, the electro-motive force of which is divided by means of a rheostat 23 so that an electro-motive force is obtained, which is lit for the compensation. If the temperature of the tube corresponds with the temperature of the medium the compensatin electro-motive force is zero. If it is above or below the temperature of the medium the compensating electro-motive force should be added to or substracted from the electro-motive force prevailing between the terminals A and B. This is obtained automatically by the electromotive force from the thermocouple l@-25 changing magnitudeand direction with the fall of temperature between the tube 2 and the medium in the tube 2 and can therefore be connected in series with the clectro-motive force between the terminals A and B- In this case the electro lytic meterE should be connected between the terminals A and C.

Another manner to avoid influence from the temperature of the neighborhood and frmn-the heat which is conducted through the metal tubes 7' and Hi from the tube I to the tube 2 is shown in Fig. 3. Here the-copper tubes 1' and It are insulated through the packings 4 and 9 from the tube l as well as from the tube 2. Furthermore the copper tubes 1' and iii are provided with glass plates 3, 8, 26 and 21 in the tube 2 as well as in the tube 1. The tubes i and 2 are equally thick and provided with a constriction at the plates 8 and 21. In the metal tubes l'lt' there are soldered junctions 5, 6 and ll for thermocouples. An only slightly heat conducting tube l3, which is insulated from the tubes i and 2 through the packing 14, carries two copper cylinder I8 and 24 containing soldered junctions l2, I5 and 2B for thermocouples. Above mentioned soldered junctions are connected together in pairs to form three thermocouples in conformity with the relations in Fig. l. The thermocouple 56 gives an electro-motive force, which varies with the velocity of the medium in the tubes 5 and 2 according to the curve A in Fig. 2, the thermocouple HI2 gives an electromotive force according to the curve B in Fig. 2 and the thermocouple I520 gives an electromotive force, which is K1+K2. The resulting electro-motive force between the terminals AB varies accordin to the curve X in Fig. 2, if the e ectro-motive force of the last mentioned thermocouple counteracts-the sum of the electro-' motive forces of the two remaining thermocouples.

Of coursethe tubes 1 and 2 in Fig. 3 may have different sections and the plates 26 and 2? may be made of metal instead of glass.

The embodiment can thus be varied considerably without departing from the scope of the invention.

Fig. 4 shows a simplified embodiment of the calorimeter according to'Fig. 3. A metal tube 1 has on its opposite ends two plates 3 and 26 inserted one in'the feed pipe I and one in the outlet pipe 2 of a heat exchanger R. The tube l is heat insulated through the packing 3" and contains three soldered junctions'for thermocouples 5 6 and II. Further there is a slightly heat conducting tube l3, which is insulated by the packing I 4' and which in each end carries a cap of metal, for example copper, l6 and 2'4, respectively. In the cap 16 there are two soldered junctions I2 and I5 and in the cap 24 a soldered junction 20 for thermocouples. The soldered junctions 5 and 6 form a theromocouple, which gives an electro-motive force varying with the velocity of a medium, for example water, running through the pipes I and 2, in conformity with the curve A in Fig. 2. The soldered junctions II and I2 form a thermocouple, the electro-motive force of which is determined by the velocity of the medium but in conformity with the curve B in Fig. 2. A third thermocouple is formed by the soldered junctions I 5 and 20 and produces an electro-motive force proportional to the fall of temperature in the device R. While help of the rheostats 2| and 22 the three above mentioned electro-motive forces are so determined and combined that an approximately straight line curve X according to Fig. 2 is obtained for the relation between the resultant electro-motive force at the terminals A-B and the heat consumption or the heat emission from the heat exchanger R.

I claim:

1. In a device for measuring the heat transition in a heat exchanger having an inlet pipe for conducting heat medium thereto and an out-. let pipe for conducting heat medium therefrom, shunt heat interchange means connected intermediate the inlet and outlet pipes and exposed to the heat medium in the former and in heat interchange relationship with the heat medium in the latter, heat conducting tubes projecting into said inlet and outlet pipes and heat insulated from said pipes, a first thermo-electrical device comprised by an element mounted in the shunt heat interchange means and adjacent the wall of the outlet pipe and a second element mounted in the shunt heat interchange means and exposed to the medium in the inlet pipe, second. thermo-electrical device comprised by an element mounted in the shunt heat interchange means and exposed to the medium in the inlet pipe and a second element mounted in the heat conducting tube in the inlet pipe, and a third thermo-electrical device comprised by an element also mounted in the heat conduct: ing tube in the inlet pipe and a second element mounted in the heat conducting tube in the outlet pipe, an electrical circuit connecting the thermo-electrical devices so that the electromotive forces developed by the first two thermoelectrical devices are cumulative and the electro-motive force developed by the third thermoelectrical device is in opposition to the total of the other two, and an electrical indicating instrument connected to the terminals of said electrical circuit.

2. In an apparatus for measuring the heat transition in a heat exchanger having an inlet pipe for conducting heat medium thereto and an outlet pipe for conducting heat medium therefrom, said inlet pipe having a constricted section therein, first and second heat interchange shunts connected intermediate the inlet and outlet pipes in heat interchange relationship with the outlet pipe, extending into the inlet pipeto be exposed to the heat medium therein and heat insulated from the wall of the inlet pipe, said second heat interchange shunt being partially disposed within the constricted section of the inlet pipe, heat conducting tubes projecting into said inlet and outlet pipes, respectively, and heat insulated'therefrom, a firsttherm'o-electrical device comprised'b y a junction mounted in the first heat interchange shunt and adjacent the wall of the outlet pipe and a second junction mounted in the first heat interchange shunt and adjacent the wall ofthe. inlet pipe, a second thermo-electrical device comprised by a first junction mounted in the second heat interchange shunt and a second junction mounted in the heat conducting tube in the inlet pipe, and a third thermo-electrical device comprised by a junction also mounted in the heat conducting tube in the inlet pipe and a second junction mounted in the heat conducting tube in the outlet pipe, an electrical circuit connecting the three thermo-electrical devices so that the electro-motive forces developed by the first two thermoelectrical devices are cumulative, and the electromotive force developed by the third thermo-electrical device is in opposition to the total of the other two, and an electrical indicating instrument connected to the terminals of said circuit.

3. In an apparatus for measuring the heat transition in a heat exchanger having an inlet pipe for conducting heat medium thereto, and an outlet pipe for conducting heat medium therefrom, said inlet pipe having a constricted sec-' tion therein, first and second heat interchange shunts connected intermediate the inlet and outlet pipes in heat interchange relationship with the wall of the outlet pipe, extending into the inlet pipe to be exposed to the heat medium therein and heat insulated from the wall of the inlet pipe, said second heat interchange shunt being partially disposed within the constricted section of the-inlet pipe, heat conducting tubes projecting into said inlet and outlet pipes, respectively, and heat insulated therefrom, a first thermo-electrical device comprised by a junction mounted in the first heat interchange shunt and adjacent the wall of the outlet pipe and a second junction mounted in the first heat interchange shunt and adjacent the wall of the inlet pipe, 2. second thermo-electrical device comprised by a first junction mounted in the second heat interchange shunt and a second junction mounted in the heat conducting tube in the inlet pipe, a third thermo-electrical device comprised by a junction also mounted in the heat conducting tube in the inlet pipe, and a second junction mounted in the heat conducting tube in the outlet pipe, a fourth thermo-electrical device comprised by a first junction mounted in the wall of the outlet pipe and a second junction mounted in the heat conducting tube in the outlet pipe, an electrical circuit connecting the four thermo-electrical devices so that the electro-motive forces developed by the first two thermo-electrical devices are cumulative, the electro-motive force developed by the third thermo-electrical device is in opposition to the other two and the electro-motive force developed by the fourth thermo-electrical device is in opposition-to the total electro-motive force of the other three thermo-electrical devices when the temperature of the medium in the outlet pipe is higher than the temperature of the Wall of the outlet pipe.

4. In an apparatus for measuring the heat transition in a heat exchanger having an inlet pipe for conducting heat medium thereto and an outlet pipe for conducting heat medium therefrom, a heat interchange shunt connected intermediate the inlet and outlet pipes extending mesa-'14s through and heatinsulat'ed from at least one wall of the latter so as to be contacted, at their respective ends by the heat medium in said pipes, heat conducting tubes projecting into said inlet pipes and heat insulated from the walls of the latter, a first thermo-electrical device comprised by first and second junctions mounted in the shunt heat interchange means adjacent the inlet and outlet pipes, respectively, a second thermoelectrical device comprised by a first junction mounted in the shunt heat interchange means adjacent the inlet pipe and a second junction mounted in the heat conducting tube in the inlet pipe, a third thermo-electrical device comprised by a first junction also mounted in the heat conducting tube in the inlet pipe and a second junction mounted in the heat conducting-tube in the outlet pipe, an electrical circuit connecting the thermo-electrical devices so that the electromotive forces developed by the first two thermoelectrical devices are cumulative and the electro motive force developed by the third thermo-electrical device is in opposition to the total of the other two, and an electrical indicating instrument connected to the terminals of said electrical circuit.

5. In an apparatus for measuring the heat transition in a heat exchanger having an inlet pipe for conducting heat medium thereto and an outlet pipe for conducting heat medium therefrom, said inlet pipe having a constricted section therein, first and. second heat interchangeshunts connected intermediate the inlet and outlet pipes extending through and heat insulated from at least the wall of the inlet pipe so as to be contacted at their respective ends by the heat medium in the latter and in heat conducting 'relationship at their other ends with the heat medium in the outlet pipe, said second heat interchange shunt extending through the wall of the inlet ipe at the constricted section. oi the latter, heat conducting tubes projecting into said inlet and outlet pipes and heat insulated from. the walls of the latter, a first thermo-electrical device comprised by a first junction mounted in the first shunt heat interchange means adjacent the inlet pipe and a second junction mounted in the first shunt heat interchange means adjacent the out:- let pipe, a second thermo-electrical device comprised by a first junction mounted in the second shunt heat interchange adjacent the inlet pipe and a second junction mounted in the heat conducting tube in the inlet pipe, a third thermoelectrical device comprised by a first junction also mounted in the heat conducting tube in the inlet pipe and a second junction mounted in the heat conducting tube in the outlet pipe, an electrical circuit connecting the thermo-electrical devices so that the electro-motive forces developed by the first two thermo-electrical devices are cumulative and the electro-motive force developed by the third thermo-electrical device is in opposition to the total of the other two, and an electrical indicating instrument connected to the terminals of said electrical circuit.

NILS GOTTFRID LINDsTRCiM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,267,757 Gibson May 28, 1918 FOREIGN PATENTS Number Country Date 33%,768 Germany Mar. 1'7, 1921 750,754 France June 6, 1933 802,704 France June 13, 1936 

